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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relationship between the promoter length of the Kluyveromyces fragilis beta-glucosidase gene and the level of its expression in Saccharomyces cerevisiae was studied by gene fusion between deleted promoter fragments of various lengths and the promoterless beta-galactosidase gene of Escherichia coli. The removal of a region from position -425 to -232 led to a tenfold increase in the expression of the gene. The same results were obtained for the reconstructed beta-glucosidase gene with the same promoter length. It is likely that the deletion of this part of the promoter removes negative regulatory elements which are functional in Saccharomyces cerevisiae. This increase in activity is the main event which may explain the high increase in gene expression (60-fold) previously observed for an upstream deletion obtained during subcloning experiments of the beta-glucosidase gene. It is also shown that the expression of the gene greatly depends upon the nature of the recipient strain, the growth phase of the cell and that of the vector carrying it.
Mol Gen Genet 1988 Jul
PMID:The promoter of the beta-glucosidase gene from Kluyveromyces fragilis contains sequences that act as upstream repressing sequences in Saccharomyces cerevisiae. 314 87

Cellobiose, the last product in cellulose degradation, is converted into two molecules of glucose by a beta-glucosidase. S. cerevisiae does posses the structural gene for a beta-glucosidase, but it is very poorly expressed; we thus decided to isolate and characterize that of Kluyveromyces fragilis. We constructed in E. coli HB101 strain a genomic library of the Kluyveromyces fragilis Y610 strain (ATCC 12424), a yeast able to grow on cellobiose and which constitutively produces the beta-glucosidase. The structural gene for beta-glucosidase was identified by its expression in E. coli. The initial isolated cosmid KF1 contained an insert of 35 Kb and by successive subcloning the insert size was reduced to 3.5 Kb (KF4). This cloned beta-glucosidase gene introduced in S. cerevisiae by transformation is expressed at a level of about 500 times that of K. fragilis. We checked by Southern hybridization that the high expression level was not due to a rearrangement of K. fragilis DNA during the cloning experiments. Nevertheless to obtain yeast transformants able to grow on cellobiose a yeast strain whose permeability to sugar is increased must be used and this last point is discussed.
Mol Gen Genet 1984
PMID:Cloning and expression of the structural gene for beta-glucosidase of Kluyveromyces fragilis in Escherichia coli and Saccharomyces cerevisiae. 609 39

A radioisotopic assay was developed to quantitate the binding of Leishmania donovani promastigotes to hamster peritoneal macrophages in vitro. The binding was temperature dependent and required no serum factors. Binding was reduced by preloading macrophages with zymosan granules or unlabeled promastigotes, but not with latex leads or opsonized erythrocytes. Binding was reduced by 10 mM EGTA that was reversible by the addition at an equimolar concentration of calcium, but not magnesium ions. Sialic acid, D-glucose, D-mannose and their derivatives reduced the binding, whereas L-fucose, D-galactose and their related sugars did not. Pretreatment of promastigotes with neuraminidase, alpha-mannosidase, alpha-N-acetylglucosaminidase or beta-glucosidase reduced their binding to macrophages. Prior trypsinization of either macrophages or promastigotes also substantially reduced the binding. At 4 degrees C, prior opsonization of promastigotes with subagglutination titers of antiserum doubled the level of binding but in combination with Protein A reduced it to 50% of its normal binding level. Prior opsonization of macrophages decreased their binding to promastigotes significantly at 4 or 37 degrees C. The results indicate that binding of Leishmania donovani promastigotes to hamster peritoneal macrophages is a ligand-receptor interaction involving their antigenic surface membrane proteins. The binding ligands of the parasites appear to have at least sialol, glucosyl, mannosyl and N-acetylglucosaminyl terminal residues as binding determinants. Thus, receptor-mediated endocytosis, defined in a broader sense, appears to be the mechanism by which leishmanias gain entry into macrophages.
Mol Biochem Parasitol 1981 Nov
PMID:Leishmania donovani-macrophage binding mediated by surface glycoproteins/antigens: characterization in vitro by a radioisotopic assay. 732 88

We have investigated the effect of disruption of the bgl1-(beta-glucosidase l-encoding) gene of Trichoderma reesei on the formation of other beta-glucosidase activities and on the induction of cellulases. To this end the bgl1 locus was disrupted by insertion of the Aspergillus nidulans amdS (acetamidase-encoding) gene. The bgl1-disrupted strain did not produce the 75 kDa extracellular beta-glucosidase on cellulose or lactose, but still formed beta-glucosidase activity on glucose, cellobiose, xylan or beta-1,3-glucan, suggesting that the enzyme(s) exhibiting this beta-glucosidase activity is (are) not encoded by bgl1. The cellulase-inducer sophorose induced the bgl1-encoded beta-glucosidase, whereas the remaining beta-glucosidase activity was induced by methyl-beta-D-glucoside. The bgl1-gene product was mainly secreted into the medium, whereas the other beta-glucosidase activity was mainly associated with the cells. A bgl1-multicopy strain formed higher amounts of cellulases than the parent strain. Nonsaturating concentrations of sophorose efficiently induced cellobiohydrolase l formation in the bgl1-multicopy strain, but less efficiently in the bgl1-disrupted strain. The multicopy strain and the parent strain were comparably efficient at saturating sophorose concentrations. The beta-glucosidase inhibitor nojirimycin strongly inhibited induction in all strains. These data suggest that the bgl1-encoded beta-glucosidase is not identical to the plasma-membrane-bound, constitutive, methyl-beta-glucoside inducible beta-glucosidase, but represents an extracellular cellulose-induced enzyme. Both enzymes contribute to rapid induction of cellulases by modifying the inducer sophorose.
Mol Microbiol 1995 May
PMID:The bgl1 gene of Trichoderma reesei QM 9414 encodes an extracellular, cellulose-inducible beta-glucosidase involved in cellulase induction by sophorose. 747 63

This computational study is a summary of how cloned beta-glucosidase subfamilies are organized. Computations were carried out using General Computer Group, Inc. (GCG) package programs. Twenty-two beta-glucosidases belonging to either cellulolytic or non-cellulolytic organisms were identified. The multialignment of a whole beta-glucosidase family is shown. Two sub-families, A and B, were clearly seen to exist. Sub-family A is further subdivided into sub-families A1 and A2. A1 includes vegetal beta-glucosidases and A2 includes prokaryotic enzymes. Sub-family B has three new sub-families, B1, B2, and B3. The enzymes in B2 are of yeast and/or fungi. Aspartic (D), glutamic (E) and histidine (H) residues, which are thought to be a part of the mechanism of the enzymatic hydrolysis are conserved. The well conserved amino acid sequences of the sub-family A are ITENGA; QUIEGA; HVD; and NEP. The well conserved amino acid sequences of the sub-family B are: SDW; and YN(R,K)(V,L)N.
Biochem Mol Biol Int 1995 May
PMID:beta-Glucosidase families revealed by computer analysis of protein sequences. 749 60

The uptake of monosaccharides (glucose and xylose) and disaccharides (cellobiose and xylobiose) was evaluated in the Streptomyces lividans mutant strain 10-164. The pleiotropic mutation had no effect on glucose uptake; however, the Vmax of xylose uptake was decreased 10-fold as compared to the wild-type strain, S. lividans 1326, and the transport system of cellobiose and xylobiose, the putative inducers of the cellulase and xylanase genes, was completely abolished resulting in a cellulase/xylanase-negative mutant. An accumulation of xylose and glucose in culture media was observed when the mutant was grown on xylobiose and cellobiose, respectively. Cell-associated beta-glucosidase and low levels of extracellular beta-glucosidase were detected in both strains. When gluconolactone, a beta-glucosidase inhibitor, was added to the medium there was no uptake of cellobiose or release of glucose by the mutant strain, whereas the uptake of cellobiose by the wild-type strain was not significantly affected. It is thus proposed that the active transport system for cellobiose and xylobiose is affected in mutant strain 10-164. Glucose and xylose production from disaccharide hydrolysis are due to beta-glucosidase and beta-xylosidase activities, which sustain the growth of the mutant strain. Clones complementing the mutation were isolated from a gene bank constructed using mutant strain 10-164. The msiK gene codes for MsiK, a 40 kDa multiple sugar import protein, which belongs to the family of ATP-binding proteins. The mutation is located in the B site which is responsible for ATP binding. This protein probably provides energy to the xylose and disaccharide transport system as a result of the hydrolysis of ATP.
Mol Microbiol 1995 Jul
PMID:A cellulase/xylanase-negative mutant of Streptomyces lividans 1326 defective in cellobiose and xylobiose uptake is mutated in a gene encoding a protein homologous to ATP-binding proteins. 749 85

Differential gene expression at the transcriptional level was examined as an initial step in the investigation of the P(i) starvation response of Brassica nigra suspension cells. Total RNA was extracted from 7-day old cells grown in media containing either no P(i), 1.25 mM or 10 mM Pi. In vitro translation was carried out using their respective poly(A)+ RNA isolates and the resultant polypeptides were separated on a high-resolution SDS-PAGE gel. Scanning densitometry identified four polypeptides (ca. 31.7, 32.3, 52.5 and 64.8 kDa) present only in the P(i)-starved samples. Screening by differential hybridization was performed on a cDNA library constructed from mRNA isolated from P(i)-starved cells. Probes prepared from mRNA from P(i)-deficient and P(i)-sufficient cells identified a number of clones representing mRNA species that were preferentially transcribed under P(i) deficiency. These phosphate starvation-responsive (psr) clones were placed into eleven groups as determined by cross-hybridization. Northern blots showed that the corresponding genes are inducible in both mild and severe P(i) starvation conditions. Preliminary sequencing identified one of the clones as being homologous to beta-glucosidases from several plant species. The possible role of beta-glucosidase during Pi starvation and the identities of the other psr genes are discussed.
Plant Mol Biol 1995 Aug
PMID:Isolation of cDNA clones of genes with altered expression levels in phosphate-starved Brassica nigra suspension cells. 764 Mar 58

Three wood-rotting fungi namely, Lenzites saepiaria, Polyporus xeranticus and Trametes gibbosa, were screened as cellulose-degraders from 20 different genera of both brown and white-rotters of Polyporaceae on the basis of their potential to degrade carboxymethylcellulose. The utilization of different carbon sources in the growth medium was studied with these fungi for identification of enzymes involved in saccharification. Carboxymethylcellulase and beta-glucosidase were identified as the two major enzymes involved in this process. Extracellular carboxymethylcellulase from L. saepiaria was purified to homogeneity and the enzyme partially characterized.
Biochem Mol Biol Int 1993 Aug
PMID:Carboxymethylcellulase from Lenzites saepiaria, a brown-rotter. 769 24

Acid phosphatase and beta-glucosidase are unique among lysosomal enzymes in that they have both high mannose and complex type sugasr chains, whereas oligosaccharide chains of lysosomal enzymes in matrix are of high mannose type. We have previously shown that beta-glucosidase was endocytosed into macrophages via an unidentified receptor different from a mannose/fucose receptor (K. Imai, Cell Struct. Funct. 13, 325-332, 1988). Here, we show that uptake of acid phosphatase purified from rat liver lysosomes into rat macrophages was inhibited by ligands for a mannose/fucose receptor and was mediated via an apparently single binding site with Kuptake of 24.7 nM. These results indicate that acid phosphatase and beta-glucosidase recognize different types of receptors even if they have similar sugar chains. Polyvalent concanavalin A which binds both to the enzyme and to macrophages specifically stimulated the uptake in a dose dependent manner, whereas wheat germ agglutinin and phytohaemagglutinin did not.
Biochem Mol Biol Int 1994 Aug
PMID:Endocytosis of lysosomal acid phosphatase; involvement of mannose receptor and effect of lectins. 780 46

A beta-glucosidase/xylosidase gene from Erwinia chrysanthemi strain D1 was cloned and sequenced. This gene, named bgxA, encodes a ca. 71 kDa protein product which, following removal of the leader peptide, resulted in a ca. 69 kDa mature protein that accumulated in the periplasmic space of E. chrysanthemi strain D1 and Escherichia coli cells expressing the cloned gene. The protein exhibited both beta-glucosidase and beta-xylosidase activities but gave no detectable activity on xylan or carboxymethyl cellulose. The enzyme was classified as a type 3 glycosyl hydrolase, but was unusual in having a truncated B region at the carboxyl-terminus. Several E. chrysanthemi strains isolated from corn produced the glucosidase/xylosidase activity but not those isolated from dicot plants. However, bgxA marker exchange mutants of strain D1 were not detectably altered in virulence on corn leaves.
Mol Gen Genet 1995 Feb 20
PMID:Cloning and characterization of the bgxA gene from Erwinia chrysanthemi D1 which encodes a beta-glucosidase/xylosidase enzyme. 789 60


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